How do I create this texture
As cegaton pointed out, the texture you are looking for is bundled in the blend on blendswap. The file is listed as CC0, so I can freely post it here.


It is a simple image that you could easily create in blender with a grid rendered with freestyle, and a text object in the corner. Below is the blend file fully ready to render a grid like the picture above. (wait for the render to fully finish before the freestyle line show up.)

Blend File click the "View Raw" button to download.